When researching tiny region of interest on a sample, researchers often employ a microscope to observe the sample. The microscope may be a conventional wide-field, fluorescent or confocal microscope. The optical configuration of such a microscope typically includes a light source, illumination optics, objective lens, sample holder, imaging optics and a detector. Light from the light source illuminates the region of interest on the sample after propagating through the illumination optics and the objective lens. Microscope objective forms a magnified image of the object that can be observed via eyepiece, or in case of a digital microscope, the magnified image is captured by the detector and sent to a computer for live observation, data storage, and further analysis. It is clear that in such a configuration, the objective lens forms a critical part of the microscope.
Many samples can be viewed directly by a microscope, that is, there is no optical material between the objective lens and the sample. However, in several other imaging configurations, such as inverted or epi-fluorescent microscope, samples are viewed through glass cover slips, glass slides and bottom plate of sample holders (e.g., Petri dishes, micro titer plates). Typically, commercially available objective lenses are designed for a specific thickness of such sample holders or covers, such as 0.17 mm microscope cover slip. When a sample holder with different thickness of bottom plate is used, the deviation from specified thickness causes significant degradation of an image quality due to spherical aberration introduced by a sample holder. A correction collar may be provided in the design on objective lens, which allows for compensation of the spherical aberration when sample is imaged through sample support of different thicknesses. In general laboratory practice, the researcher using the microscope adjusts a spherical aberration correction setting by: (1) manual rotation of the collar, while observing the live image on the computer screen, (2) setting the collar to a known sample holder thickness using a scale placed on the microscope objective.
For an automated microscope system, it is not always able to access the objective lenses to correct spherical aberration setting of the objective lens. The user's ability to access the objective lenses to correct spherical aberration setting may be restricted due to laser safety regulation for a laser scanning microscope, or the physical access may be limited due to a self-enclosed design automated microscope (i.e. if the objective lens is located in the middle of the instrument and is surrounded by other components of the microscope).
The utilization of a motorized (or automated) spherical aberration correction system in a microscope will enable a user to simply and effectively correct spherical aberration of objective lenses in order to obtain a clear image of the sample. Therefore, there is a need for a system and method that enables the user to adjust the spherical aberration correction setting of objective lenses, or to perform the imaging of multiple samples that require different setting of spherical aberration correction in an automated mode.